Well done
Excellent job on the creature and the rock, good attention to detail. At first, I thought it was an under-water scene; the huge, bright moon and vague blue sky make it seem like the sun shining into the depths. Judging from what looks like a river in the background, I'm assuming that isn't the case.
I don't get a very good sense of it's size. I like to think of it as massive, but sheer rock isn't the best reference.